1. Field of the Invention
The present invention relates to comprehensive processing of various fuels, and in particular to a method for processing pulverized solid fuel by heat.
This invention can find wide application in the production of transportable fuels, electric power, chemical and commercial materials.
2. Description of the Prior Art
There is known in the art a method for processing a solid fuel, wherein corundum balls of 10 to 12 mm in diameter are used as the heat carrier for heating the fuel. The balls are preheated in the first chamber of a two-chamber reactor by furnace gases. The second chamber, having a heated solid heat carrier continuously fed thereinto from top, is used for heating, drying, coking and partial gasification of a pulverized solid fuel which, in a mixture with gas and vapor, flows upwardly through a dense layer of the heat carrier. The resultant commercial products are hot small coke, tar and gas (cf. Perepelitza A. L. et al. "Utilization of Solid Heat Carrier in the Flow Process of Continuous Coking of Coals in the Coal Fields of Irkutsk Region").
There is also known a method for processing a pulverized solid fuel, wherein a flow of pulverized fuel is fed upwardly. The fuel is heated by a downward countercurrent flow of larger-in-size particles of a solid heat carrier (sand, shot, etc.) immiscible with the fuel. Water vapor is fed together with the solid fuel to the reactor. Pyrolysis is effected simultaneously with the coal gasification process. The heat carrier is heated by combustion gas immiscible with the products of pyrolysis and gasification.
The above method is characterized by products of pyrolysis which mix with steam and blue gas, which complicate the clean-up and use of pyrolysis products, as well as the apparatus construction.
There is known a method for pyrolysis of pulverized solid fuel, such as coal, wherein the fuel is first, dried and then heated to a temperature of 500.degree. C. in the first zone of pyrolysis by the heat evolved from combustion gas with the resultant formation of small coke and pyrolysis products. The small coke is fed to the second zone of pyrolysis to be heated therein to a temperature of 1000.degree. C. by a gaseous heat carrier with the resultant formation of residual products of pyrolysis and small coke, their subsequent separation and collection as commercial products (cf. U.S.S.R. Inventor's Certificate No. 335,267).
The above-described method is characterized by a solid residue of fuel and small coke, resulting from pyrolysis and gasification, which is normally used together with tar in furnaces of a boiler incorporated in a power plant, and thus causes excessive slagging in the boiler and adds to the pollution of the environment as harmful refuse of sulfur, nitrogen oxides, as well as ash particles are disposed of. The yield of valuable products is negligible and, to make things worse, the products contain inert admixtures.